Anthropologists have confirmed that features of the human body have been shaped by hunting on the run

Dozens of years ago, scientists put forward the hypothesis that the appearance of the genus Homo arose under the influence of a specific task: hunting game by running. Despite the general logicality of this version, a number of counterarguments were put forward against it: running is energy-consuming, and there are not so many examples of "running hunting" in the XX century. It seems that now both these objections are removed.

An international group of scientists, whose work was published in the journal Nature Human Behaviour, aimed to confirm or refute the hypothesis of endurance running. Its supporters argue that the main differences between the genus Homo and Australopithecus and other pre-human primates - in the adaptation of our skeleton and soft tissues to running. From this perspective, running was already used by the earliest Homo to efficiently obtain meat, which allowed them to dramatically accelerate the development of energy-consuming subsystems - such as the brain. In other words, a significant part of all humanisation within the framework of this hypothesis falls precisely on the ability of humans to run for endurance.

At first glance, the hypothesis looks attractive because it explains a large set of unusual facts at the expense of a minimum of assumptions. For example, the gait of humans, including during running, is unique among all known and extinct species. It is known that modern man - excluding his civilised forms, where only athletes have retained such capabilities - can catch a cheetah by exhausting it by running in the African sun.

Similarly, Bushmen still trap kudu antelopes. Although cheetahs and ungulates are faster than us at short and medium distances, they are much less winded on the run, so they overheat more and after 30-35 kilometres on a hot day can no longer run. The speed of a human being has not yet dropped, which is why he catches up with the pursued animals.

Humans can run up to 300 kilometres a day, an ability not possessed by other known mammals, including horses. Perhaps this is only achievable for ostriches (however, this is difficult to establish reliably due to the difficulty of motivating them in experiments).

But for all the strengths of the hypothesis, it has its critics in the academic environment. Some of them note that a person in a typical "hunting on the run" spends a lot of kilocalories - sometimes, as with kudu, more than a thousand. Can we assume that this was a reasonable hunting strategy for early Homo? This question is asked by some researchers.

In their view, getting food on foot was more efficient, because it required less energy. Others point out that today, outside of certain regions of Africa, "hunting by running" is virtually non-existent. A truly efficient hunting strategy, the scientists believe, should be more widespread.

The authors of the new paper performed calculations to find out how much energy and time early humans had to expend to chase animals of various classes by running. It turns out that getting food "on foot" is very time-consuming and, as a result, less energy-efficient than the seemingly more energy-intensive running.

For example, chasing a beast at four kilometres per hour would take approximately two hours. In that time, a person would cover eight kilometres and expend 60 kilocalories per hour. Chasing a simulated game animal at 10 kilometres per hour (slow running) would take only 24 minutes. As a result, the energy output (kilocalories in prey meat) per unit of time spent while running increases fivefold. Even if you use a combination of walking and slow running for hunting, the energy output per unit of time increases two to three times.

The researchers noted that, in general, the transition to running in humans very slightly increases energy expenditure. Slow running requires 69 kilocalories per kilometre, while walking requires 58.5 kilocalories per kilometre. The calculations, of course, apply to moderate-mass trained people, since before modern civilisation all hunters, by modern standards, were like that.

Scientists have tried to calculate how significant this energy expenditure is when hunting antelope (oryx). Today, the oryx can be driven by running, but whether it can be driven on foot is not known.

The researchers took a model of hunting this antelope on foot, in the form of a pursuit at a speed of four kilometres per hour for 10 consecutive hours. The scientists then took the same 40 kilometres of stalking distance, but modelled a human hunter covering it with a slow jog in four hours.

It turned out that the energy net result for the hunter-runner was almost unchanged. If we subtract from the kilocalories obtained from eating antelope meat those kilocalories spent on catching up with it, then in the running version the hunter received 160,016 kilocalories. And the modelled "foot hunter" - 160 436 kilocalories, because he spent less energy to catch up with the game. At the same time, the runner spent 2.5 times less time for hunting.

Thus, modelling has shown that energy expenditures for running differ so slightly (for an uncivilised person) from walking that they cannot be an argument against the hypothesis of endurance running.

Then the researchers took up the second thesis of the critics: the rarity of examples of hunting on the run nowadays. They turned to ethnographic observations of the 19th and early 20th centuries, trying to find there references to such a long hunt. In total, they managed to find 400 such facts in ethnographic literature. They concerned 272 regions of the Earth's landmass.

From all this the researchers concluded about the validity of the hypothesis of endurance running. Although their arguments are quite convincing, it should be noted that they did not address a number of other controversial points of the hypothesis.

For example, it is not quite obvious today that the late Australopithecines were adapted for prolonged running worse than Homo: they, too, have rather long leg bones and a stiff foot, necessary for running. It follows that, in practice, the hypothesis of running for endurance cannot refer only to the representatives of the genus Homo, but also affects its ancestors, in whom erectness, to all appearances, arose for quite other, non-running, reasons.